A temporary ban on mangoes from the Commonwealth of the Northern Mariana Islands (CNMI) to Guam is in place after researchers detected the mango fruit borer in Saipan. The pest feeds on the pulp and seed of mangoes, causing internal damage to the fruit.
During a site visit two months ago, researchers from the University of Guam found larvae inside mangoes. "On one of the mango trees, there was this larva, this worm, chewing up the inside of the mangoes," said Guam Department of Agriculture's biosecurity chief and state entomologist Christopher Rosario. A DNA sample was sent to an off-island lab, where the insect was identified as a mango fruit borer.
Following confirmation, the Department of Agriculture temporarily suspended mango imports from the CNMI. According to Rosario, the insect is a moth native to Southeast Asia and northern Australia. It lays eggs on mangoes, and larvae bore into the fruit. "It's very difficult to tell whether a mango is infested with mango fruit borer, because there is another mango pest that we have. It's called the mango seed weevil, which generally bores into the seed. This bores into the fruit, so it eats the fruit itself," he said.
Although the ban is in effect, Rosario said University of Guam entomologist Dr. Daniel Johnson suspects the pest may already be present on Guam. "It's still kind of in the works. We're still trying to figure out if mango fruit borer has made its way to Guam," Rosario noted. "I don't want to start ringing the alarms yet until we get full confirmation. But Dr. Johnson suspects we may also have it already."
Mangoes have cultural and economic relevance in Guam, with Hagat hosting an annual festival dedicated to the crop. "Mangoes are a huge part of our lives. As far as its impacts, we know there is a lot of mango, so there's a lot of potential growth for this mango fruit borer to also invade. So for me, I say the impact could be devastating," Rosario said.
The Department of Agriculture points to the invasive hog plum beetle as an example of the long-term impact of invasive pests. The beetle, detected in 2023, has spread across the island, defoliating Spanish plum trees. Rosario stressed that integrated pest management strategies for the mango fruit borer will be necessary. "This is why the research is very important, to look at what potential biocontrol agents are for this pest. What are safe pesticides or insecticides that we can use? And what other cultural methods can help us better manage this mango fruit borer if it is on Guam?"
The temporary ban is intended to protect Guam's mango industry while officials train inspectors to identify and manage the pest at the border.
Source: Kuam News